EP0285393A2 - Wavelength Conversion Element - Google Patents
Wavelength Conversion Element Download PDFInfo
- Publication number
- EP0285393A2 EP0285393A2 EP88302832A EP88302832A EP0285393A2 EP 0285393 A2 EP0285393 A2 EP 0285393A2 EP 88302832 A EP88302832 A EP 88302832A EP 88302832 A EP88302832 A EP 88302832A EP 0285393 A2 EP0285393 A2 EP 0285393A2
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- EP
- European Patent Office
- Prior art keywords
- wavelength
- conversion element
- semiconductor laser
- tunable
- saturable absorption
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/0607—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying physical parameters other than the potential of the electrodes, e.g. by an electric or magnetic field, mechanical deformation, pressure, light, temperature
- H01S5/0608—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying physical parameters other than the potential of the electrodes, e.g. by an electric or magnetic field, mechanical deformation, pressure, light, temperature controlled by light, e.g. optical switch
- H01S5/0609—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying physical parameters other than the potential of the electrodes, e.g. by an electric or magnetic field, mechanical deformation, pressure, light, temperature controlled by light, e.g. optical switch acting on an absorbing region, e.g. wavelength convertors
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/0601—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium comprising an absorbing region
- H01S5/0602—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium comprising an absorbing region which is an umpumped part of the active layer
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/0607—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying physical parameters other than the potential of the electrodes, e.g. by an electric or magnetic field, mechanical deformation, pressure, light, temperature
- H01S5/0608—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying physical parameters other than the potential of the electrodes, e.g. by an electric or magnetic field, mechanical deformation, pressure, light, temperature controlled by light, e.g. optical switch
- H01S5/0609—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying physical parameters other than the potential of the electrodes, e.g. by an electric or magnetic field, mechanical deformation, pressure, light, temperature controlled by light, e.g. optical switch acting on an absorbing region, e.g. wavelength convertors
- H01S5/0611—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying physical parameters other than the potential of the electrodes, e.g. by an electric or magnetic field, mechanical deformation, pressure, light, temperature controlled by light, e.g. optical switch acting on an absorbing region, e.g. wavelength convertors wavelength convertors
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/062—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes
- H01S5/0625—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes in multi-section lasers
- H01S5/06255—Controlling the frequency of the radiation
- H01S5/06256—Controlling the frequency of the radiation with DBR-structure
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/062—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes
- H01S5/0625—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes in multi-section lasers
- H01S5/06255—Controlling the frequency of the radiation
- H01S5/06258—Controlling the frequency of the radiation with DFB-structure
Definitions
- the present invention relates to semiconductor elements, more particularly, to those for use in communication, information processing and the like which are adapted to convert incident or input light having a given wavelength to outgoing or output light having a desired wavelength.
- wavelength conversion elements heretofore proposed include one which utilizes generation of second harmonic wave that is non-linear optical effect and which achieves wavelength conversion to half the original wavelength. More particularly, as Taniuchi et al. reported in an international conference, i.e., Conference on Lasers and Electro-optics, 1986, introduction of a semiconductor laser beam having a wavelength of 0.84 ⁇ m in an amount of 40 mW into a proton-exchanged light waveguide of lithium niobate substrate generates a laser beam having a wavelength of 0.42 ⁇ m in an amount of 0.4 mW (WR3 presentation). However, the conventional wavelength conversion element utilizing generation of second harmonic wave is disadvantageous since it only allows conversion of wavelength to half the wavelength of the input light.
- multi-electrode distributed feedback reflector type semiconductor lasers as described in, for example, JP-A-61-290789 which discloses a multi-electrode distributed feedback type semiconductor laser device comprising a diffractive grating over the whole length of the resonator and at least two electrodes in the direction of light axis, the electrodes being controllable with respect to their injection current supply independently of each other.
- An object of the present invention is to provide a wavelength conversion element capable of converting input light having a given wavelength to light having a desired wavelength.
- Another object of the present invention is to provide a wavelength conversion element capable of controlling the lasing wavelength at a desired wavelength with changing the operational conditions.
- the present invention provides a wavelength conversion element comprising a substrate having integrated thereon close to each other a wavelength-tunable semiconductor laser portion which oscillates in a single mode and whose oscillation wavelength can be set up at a desired value within a given wavelength range by changing operational conditions, and a saturable absorption region optically connected to the wavelength-tunable semiconductor laser.
- the wavelength-tunable laser when input light is introduced into the saturable absorption region, the wavelength-tunable laser is put in negative temperature state with a slight amount of carriers supplied from the saturable absorption while the saturable absorption region is being saturated. Then, when the saturable absorption region has been saturated and light output increases abruptly, output light having a given wavelength is generated from the wavelength-tunable laser in the negative temperature state. Selection of the wavelength is performed by changing the operational conditions such as controlling the amount of currents of some electrodes to be injected.
- Fig. 1 illustrates a first embodiment of the present invention.
- reference numeral 1 designates an n-type InP substrate having provided thereon a 1.5 ⁇ m wavelength GaInAsP active layer 2, which has provided thereon a 1.3 ⁇ m wavelength GaInAsP waveguide layer 3.
- a refractive grating 4 is provided on the waveguide layer 3 above the active layer 2 such that the grating 4 forms an interface between the p-InP clad and the waveguide layer 3.
- Injection electrodes 6 and 7 are arranged on the clad layer 5 separate from each other in the direction of the light axis which extends horizontally along the length of the element as viewed in Fig. 1.
- the distance between the electrodes 6 and 7 is generally from 2 ⁇ m to 10 ⁇ m and preferably about 5 ⁇ m.
- an injection electrode 8 having a polarity opposite to that of the injection electrodes 6 and 7.
- Anti-reflection coating layers 9 and 10 are provided on the side surfaces, i.e., light input side and light output side of the light conversion element in order to prevent reflection of the light.
- a groove 11 for establishing electrical insulation is provided in the clad 5.
- the depth of the groove 11 is determined so as to attain effective insulation between a wavelength-tunable semiconductor laser portion 13 and a saturable absorption region 12. However, the groove 11 should not reach the grating or corrugation 4.
- the depth of the groove 11 is from 0.5 ⁇ m to 1.5 ⁇ m and preferably about 1.0 ⁇ m.
- the wavelength conversion element of the present invention can be fabricated according to conventional method as described, for example, in Electronics Letters, vol. 23, No. 20, p.1088 (1987). More particularly, it can be fabricated as follows:
- non-doped GaInAsP active and guide layers were grown on an n-type InP substrate.
- corrugation grating was formed on the guide layer, a p-type InP clad layer and a GaInAsP cap layer were grown on the grating.
- a selective chemical etching technique was used to make a mesa-stripe of the double-heterostructure region, and surrounding InP layers consisting of a p-InP and an n-InP were grown on the etched surface by liquid phase epitaxy.
- Contacts were formed by evaporating An-Zn-Ni and An-Sn onto the p- and n-type sides respectively.
- the p-type electrode was divided into three sections by selective etching the An-Zn-Ni metal using KI etchant, and the p-electrode of the saturable absorption region was etched off.
- the GaInAsP cap layer and p-InP clad layer were ion-beam etched to obtain proper isolation among the electrodes and the saturable absorption region.
- Resistance between p-type electrodes was set at about 100 ⁇ (ohms), and resistance between the saturable absorption region and p-type electrode was about 1 k ⁇ (kilo-ohm).
- a portion 12 encircled by broken line acts as a saturable absorption region since no injection of current does occur there.
- the saturable absorption region 12 has characteristics shown in Fig. 2 which will be described in detail hereinbelow.
- the rest portion other than the saturable absorption region 12 exhibits the function of a wavelength-tunable laser as a multi-electrode distributed feedback type semiconductor laser as described in JP-A-61-290789 laid-open on December 20, 1986. That is, by changing the intensity of current I1 passed in the injection electrode 6 and current I2 passed in the injection electrode 7, there is formed in the inside of the laser a difference in the distribution of the density of carriers, which causes the change in the refractive index of the laser due to the gradient of the density of carriers.
- the optical pitch of the diffractive grating 4 changes in the direction of the light axis, thus allowing it to continuously change the oscillation wavelength in a single mode within a certain wavelength range which is a function of various parameters such as cavity length, resistance between electrodes 6 and 7, etc. as is known in the art.
- Fig. 2 plots period of time "t" which passes from the introduction of the input light P in on the horizontal axis versus the intensity of light output from the saturable absorption region 12 on the vertical axis.
- the intensity of light output gradually increases at a low output until a certain time t d by the action of the saturable absorption region 12 followed by an abrupt increase after the time t d .
- the time t d depends on the intensity of input light.
- the time t d is 0.8 ns.
- sum I of the injection current I1 and I2 supplied to the wavelength-tunable laser 13 is set up to 0.94 to 0.998 time as large as the threshold value I th of the laser 13, the laser 13 falls in negative temperature state due to carriers generated by the absorption of input light P in within the time span of t d to oscillate light in a single mode whose wavelength is determined by the proportion of the injection current I1 and the injection current I2.
- the oscillation wavelength of the laser can be changed freely in a wavelength range in which the active layer 2 has a gain by changing the proportion of the injection current I1 and the injection current I2.
- laser light having a wavelength corresponding thereto can be obtained chronologically.
- the presence of the saturable absorption region 12 is essentially important. If there is provided no saturable absorption region 12 and only the wavelength-tunable laser 13 is provided, the element remains to amplify the wavelength of the input light but fails to function as a wavelength conversion element.
- Fig. 3 illustrates a second embodiment of the present invention.
- the second embodiment differs from the first embodiment shown in Fig. 1 in the following points.
- the element serves as a wavelength conversion element as in the first embodiment illustrated in Fig. 1.
- the wavelength-tunable laser portion 13 of the wavelength conversion element can be of any form.
- Fig. 4 illustrates a third embodiment of the wavelength conversion element according to the present invention in which the wavelength-tunable laser portion reported by Y. Abe et al. in Electronics Letters, vol. 17, No.25, p.945 (1981) is applied.
- the wavelength-tunable laser portion 13 of the wavelength conversion element of this type is a so-called distributed reflector type semiconductor laser which comprises an active layer 2 that lacks a diffractive grating, a diffractive grating 4 provided only at a position on the left-hand side of the active layer 2 and below an electrode 31.
- the diffractive grating 4 serves as a light reflecting portion.
- the wavelength conversion element according to this embodiment can be fabricated similarly as in the case of the element according to the first embodiment except for the butt-jointed portion which can also be fabricated in a conventional manner as described, for example, in Electronics Letters, vol. 17, No. 25, p.945 (1981).
- the lasing wavelength changes with the change in the refractive index of the diffractive grating 4, the change in the refractive index being attained, for example, by varying the intensity of the injection current I1 to be introduced into the electrode 31 while maintaining the intensity of the current I2 at a predetermined level which is slightly lower than that of the threshold current (e.g., 0.94 to 0.998 time as high as the threshold current) to vary the proportion of I1/I2.
- the element functions as a wavelength conversion element.
- the wavelength-tunable laser portion and the saturable absorption region together enable conversion of the input light introduced in the saturable absorption region to a laser beam having a desired wavelength within a certain wavelength range. Therefore, multiplication and exchange of information can be performed, and this results in the realization of a large capacity information processing due to wavelength multiplication.
- an electrode may be attached to the saturable absorption region 12 in order to pass current to control the amount of saturable absorption.
- the wavelength conversion mechanism of the present invention operates regardless of whether or not current is injected to the saturable absorption region.
Abstract
Description
- The present invention relates to semiconductor elements, more particularly, to those for use in communication, information processing and the like which are adapted to convert incident or input light having a given wavelength to outgoing or output light having a desired wavelength.
- In the field of light information processing, light switching and the like in which processing of information is carried out using light which carries or bears information without converting light signals to electric signals, it has been desired to realize a wavelength conversion element which can convert input light having a given wavelength to output light having a desired wavelength since such element allows processing of information in large capacity by means of multiplex wavelengths.
- Conventional types of wavelength conversion elements heretofore proposed include one which utilizes generation of second harmonic wave that is non-linear optical effect and which achieves wavelength conversion to half the original wavelength. More particularly, as Taniuchi et al. reported in an international conference, i.e., Conference on Lasers and Electro-optics, 1986, introduction of a semiconductor laser beam having a wavelength of 0.84 µm in an amount of 40 mW into a proton-exchanged light waveguide of lithium niobate substrate generates a laser beam having a wavelength of 0.42 µm in an amount of 0.4 mW (WR3 presentation). However, the conventional wavelength conversion element utilizing generation of second harmonic wave is disadvantageous since it only allows conversion of wavelength to half the wavelength of the input light.
- On the other hand, in semiconductor lasers whose lasing wavelength can be tuned electrically, various types of semiconductor lasers are known as described, for example, in Y. Abe et al., Electronics Letters, vol. 17, No. 25, 10th December 1981, pages 945-947 which discloses integrated lasers with butt-jointed built-in distributed Bragg reflection waveguides in which an active guide and a built-in external guide on the surface of which is formed corrugation are butt-jointed.
- Furthermore, there have been proposed multi-electrode distributed feedback reflector type semiconductor lasers as described in, for example, JP-A-61-290789 which discloses a multi-electrode distributed feedback type semiconductor laser device comprising a diffractive grating over the whole length of the resonator and at least two electrodes in the direction of light axis, the electrodes being controllable with respect to their injection current supply independently of each other.
- An object of the present invention is to provide a wavelength conversion element capable of converting input light having a given wavelength to light having a desired wavelength.
- Another object of the present invention is to provide a wavelength conversion element capable of controlling the lasing wavelength at a desired wavelength with changing the operational conditions.
- Therefore, the present invention provides a wavelength conversion element comprising a substrate having integrated thereon close to each other a wavelength-tunable semiconductor laser portion which oscillates in a single mode and whose oscillation wavelength can be set up at a desired value within a given wavelength range by changing operational conditions, and a saturable absorption region optically connected to the wavelength-tunable semiconductor laser.
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- Fig. 1 is a longitudinal cross-sectional view of a wavelength conversion element according to a first embodiment of the present invention;
- Fig. 2 is a graph showing the time-dependent change in the light output of the saturable absorption region of a wavelength conversion element of the present invention;
- Fig. 3 is a longitudinal cross-sectional view of a wavelength conversion element according to a second embodiment of the present invention; and
- Fig. 4 is a longitudinal cross-sectional view of a wavelength conversion element according to a third embodiment of the present invention.
- In the construction of the wavelength conversion element of the present invention, when input light is introduced into the saturable absorption region, the wavelength-tunable laser is put in negative temperature state with a slight amount of carriers supplied from the saturable absorption while the saturable absorption region is being saturated. Then, when the saturable absorption region has been saturated and light output increases abruptly, output light having a given wavelength is generated from the wavelength-tunable laser in the negative temperature state. Selection of the wavelength is performed by changing the operational conditions such as controlling the amount of currents of some electrodes to be injected.
- A preferred embodiment of the present invention will be described with reference to the attached drawings in which Fig. 1 illustrates a first embodiment of the present invention. In Fig. 1,
reference numeral 1 designates an n-type InP substrate having provided thereon a 1.5 µm wavelength GaInAsPactive layer 2, which has provided thereon a 1.3 µm wavelengthGaInAsP waveguide layer 3. Arefractive grating 4 is provided on thewaveguide layer 3 above theactive layer 2 such that thegrating 4 forms an interface between the p-InP clad and thewaveguide layer 3.Injection electrodes clad layer 5 separate from each other in the direction of the light axis which extends horizontally along the length of the element as viewed in Fig. 1. The distance between theelectrodes substrate 1, or the surface of thesubstrate 1 opposite to that on which theactive layer 2 is provided, is attached aninjection electrode 8 having a polarity opposite to that of theinjection electrodes Anti-reflection coating layers groove 11 for establishing electrical insulation is provided in theclad 5. The depth of thegroove 11 is determined so as to attain effective insulation between a wavelength-tunablesemiconductor laser portion 13 and asaturable absorption region 12. However, thegroove 11 should not reach the grating orcorrugation 4. Generally, the depth of thegroove 11 is from 0.5 µm to 1.5 µm and preferably about 1.0 µm. - The wavelength conversion element of the present invention can be fabricated according to conventional method as described, for example, in Electronics Letters, vol. 23, No. 20, p.1088 (1987). More particularly, it can be fabricated as follows:
- At first, non-doped GaInAsP active and guide layers were grown on an n-type InP substrate. After 2400 Angstrom period corrugation grating was formed on the guide layer, a p-type InP clad layer and a GaInAsP cap layer were grown on the grating. In order to fabricate a buried heterostructure, a selective chemical etching technique was used to make a mesa-stripe of the double-heterostructure region, and surrounding InP layers consisting of a p-InP and an n-InP were grown on the etched surface by liquid phase epitaxy. Contacts were formed by evaporating An-Zn-Ni and An-Sn onto the p- and n-type sides respectively. The p-type electrode was divided into three sections by selective etching the An-Zn-Ni metal using KI etchant, and the p-electrode of the saturable absorption region was etched off. The GaInAsP cap layer and p-InP clad layer were ion-beam etched to obtain proper isolation among the electrodes and the saturable absorption region. Resistance between p-type electrodes was set at about 100Ω (ohms), and resistance between the saturable absorption region and p-type electrode was about 1 kΩ(kilo-ohm).
- In Fig. 1, a
portion 12 encircled by broken line acts as a saturable absorption region since no injection of current does occur there. Thesaturable absorption region 12 has characteristics shown in Fig. 2 which will be described in detail hereinbelow. - The rest portion other than the
saturable absorption region 12 exhibits the function of a wavelength-tunable laser as a multi-electrode distributed feedback type semiconductor laser as described in JP-A-61-290789 laid-open on December 20, 1986. That is, by changing the intensity of current I₁ passed in theinjection electrode 6 and current I₂ passed in theinjection electrode 7, there is formed in the inside of the laser a difference in the distribution of the density of carriers, which causes the change in the refractive index of the laser due to the gradient of the density of carriers. With this change, the optical pitch of thediffractive grating 4 changes in the direction of the light axis, thus allowing it to continuously change the oscillation wavelength in a single mode within a certain wavelength range which is a function of various parameters such as cavity length, resistance betweenelectrodes - In the above construction, when input light Pin having a wavelength which can be absorbed by the
active layer 2 is introduced, light output from thesaturable absorption region 12 is as illustrated in Fig. 2. Fig. 2 plots period of time "t" which passes from the introduction of the input light Pin on the horizontal axis versus the intensity of light output from thesaturable absorption region 12 on the vertical axis. As will be obvious from this graph, the intensity of light output gradually increases at a low output until a certain time td by the action of thesaturable absorption region 12 followed by an abrupt increase after the time td. The time td depends on the intensity of input light. For example, when the input light is 50 µW, the time td is 0.8 ns. In this case, when sum I of the injection current I₁ and I₂ supplied to the wavelength-tunable laser 13 is set up to 0.94 to 0.998 time as large as the threshold value Ith of thelaser 13, thelaser 13 falls in negative temperature state due to carriers generated by the absorption of input light Pin within the time span of td to oscillate light in a single mode whose wavelength is determined by the proportion of the injection current I₁ and the injection current I₂. - The oscillation wavelength of the laser can be changed freely in a wavelength range in which the
active layer 2 has a gain by changing the proportion of the injection current I₁ and the injection current I₂. Thus, chronologically changing the proportion of the injection current I₁ and the injection current I₂, laser light having a wavelength corresponding thereto can be obtained chronologically. - In the above operation, the presence of the
saturable absorption region 12 is essentially important. If there is provided nosaturable absorption region 12 and only the wavelength-tunable laser 13 is provided, the element remains to amplify the wavelength of the input light but fails to function as a wavelength conversion element. - Fig. 3 illustrates a second embodiment of the present invention. The second embodiment differs from the first embodiment shown in Fig. 1 in the following points.
- (1) The injection electrode provided on the upper end of the element is divided into 3 parts, i.e.,
upper electrodes electrode 21 and theelectrode 23 are connected electrically to each other, and the tuned wavelength can be varied by changing the proportion of the injection current I₁ injected to the electrodes and the injection current I₂ injected to thecentral electrode 22. - (2) The
diffractive grating 4 is not uniform but shifted by 1/4 phase to below thecentral electrode 22. Although it can be omitted, the phase shift, if present, ensures oscillation of only one of the two longitudinal modes positioned on the both sides of Bragg wavelength. - In the above construction, the element serves as a wavelength conversion element as in the first embodiment illustrated in Fig. 1.
- The wavelength-
tunable laser portion 13 of the wavelength conversion element can be of any form. Fig. 4 illustrates a third embodiment of the wavelength conversion element according to the present invention in which the wavelength-tunable laser portion reported by Y. Abe et al. in Electronics Letters, vol. 17, No.25, p.945 (1981) is applied. - The wavelength-
tunable laser portion 13 of the wavelength conversion element of this type is a so-called distributed reflector type semiconductor laser which comprises anactive layer 2 that lacks a diffractive grating, adiffractive grating 4 provided only at a position on the left-hand side of theactive layer 2 and below anelectrode 31. Thediffractive grating 4 serves as a light reflecting portion. The wavelength conversion element according to this embodiment can be fabricated similarly as in the case of the element according to the first embodiment except for the butt-jointed portion which can also be fabricated in a conventional manner as described, for example, in Electronics Letters, vol. 17, No. 25, p.945 (1981). - In the above construction, the lasing wavelength changes with the change in the refractive index of the
diffractive grating 4, the change in the refractive index being attained, for example, by varying the intensity of the injection current I₁ to be introduced into theelectrode 31 while maintaining the intensity of the current I₂ at a predetermined level which is slightly lower than that of the threshold current (e.g., 0.94 to 0.998 time as high as the threshold current) to vary the proportion of I₁/I₂. Thus, the element functions as a wavelength conversion element. - As stated above, according to the present invention, the wavelength-tunable laser portion and the saturable absorption region together enable conversion of the input light introduced in the saturable absorption region to a laser beam having a desired wavelength within a certain wavelength range. Therefore, multiplication and exchange of information can be performed, and this results in the realization of a large capacity information processing due to wavelength multiplication.
- Although no current is injected to the
saturable absorption region 12 in the embodiments illustrated in Figs. 1, 2 and 3, an electrode may be attached to thesaturable absorption region 12 in order to pass current to control the amount of saturable absorption. The wavelength conversion mechanism of the present invention operates regardless of whether or not current is injected to the saturable absorption region. - While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.
Claims (4)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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JP77670/87 | 1987-03-31 | ||
JP62077670A JPH0656908B2 (en) | 1987-03-31 | 1987-03-31 | Wavelength conversion element |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0285393A2 true EP0285393A2 (en) | 1988-10-05 |
EP0285393A3 EP0285393A3 (en) | 1989-07-26 |
EP0285393B1 EP0285393B1 (en) | 1993-06-16 |
Family
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP88302832A Expired - Lifetime EP0285393B1 (en) | 1987-03-31 | 1988-03-30 | Wavelength conversion element |
Country Status (4)
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US (1) | US4856005A (en) |
EP (1) | EP0285393B1 (en) |
JP (1) | JPH0656908B2 (en) |
DE (1) | DE3881737T2 (en) |
Cited By (5)
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DE3834929A1 (en) * | 1988-10-13 | 1990-04-19 | Siemens Ag | Optical waveguide reflector for optoelectronic applications and lasers |
EP0409177A2 (en) * | 1989-07-17 | 1991-01-23 | Siemens Aktiengesellschaft | Optical feedback amplifier |
EP0484923A2 (en) * | 1990-11-07 | 1992-05-13 | Nippon Telegraph And Telephone Corporation | Semiconductor wavelength conversion device |
DE4301830A1 (en) * | 1993-01-23 | 1994-07-28 | Ant Nachrichtentech | 3-section DFB semiconductor laser with extended wavelength tuning range |
WO2003009438A2 (en) * | 2001-07-18 | 2003-01-30 | Marconi Uk Intellectual Property Ltd | Wavelength division multiplex optical wavelength converter |
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Publication number | Priority date | Publication date | Assignee | Title |
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JPH0719928B2 (en) * | 1986-11-26 | 1995-03-06 | 日本電気株式会社 | Optical filter element |
DE3836802A1 (en) * | 1988-10-28 | 1990-05-03 | Siemens Ag | SEMICONDUCTOR LASER ARRANGEMENT FOR HIGH OUTPUT PERFORMANCE IN LATERAL BASIC MODE |
JPH02244128A (en) * | 1989-03-17 | 1990-09-28 | Fujitsu Ltd | Optical switch using laser diode |
DE69011921T2 (en) * | 1989-04-04 | 1995-03-02 | Canon Kk | Semiconductor laser with variable emission wavelength and selective wavelength fitter and method for operating the same. |
US5088097A (en) * | 1990-04-04 | 1992-02-11 | Canon Kabushiki Kaisha | Semiconductor laser element capable of changing emission wavelength, and method of driving the same |
JPH0457384A (en) * | 1990-06-27 | 1992-02-25 | Mitsubishi Electric Corp | Semiconductor laser |
JP2804838B2 (en) * | 1990-10-11 | 1998-09-30 | 国際電信電話株式会社 | Tunable semiconductor laser |
US5325392A (en) * | 1992-03-06 | 1994-06-28 | Nippon Telegraph And Telephone Corporation | Distributed reflector and wavelength-tunable semiconductor laser |
US6717964B2 (en) * | 2001-07-02 | 2004-04-06 | E20 Communications, Inc. | Method and apparatus for wavelength tuning of optically pumped vertical cavity surface emitting lasers |
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KR101381235B1 (en) * | 2010-08-31 | 2014-04-04 | 한국전자통신연구원 | Dual mode semiconductor laser and terahertz wave apparatus using the same |
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Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3834929A1 (en) * | 1988-10-13 | 1990-04-19 | Siemens Ag | Optical waveguide reflector for optoelectronic applications and lasers |
EP0409177A2 (en) * | 1989-07-17 | 1991-01-23 | Siemens Aktiengesellschaft | Optical feedback amplifier |
EP0409177A3 (en) * | 1989-07-17 | 1991-09-18 | Siemens Aktiengesellschaft | Optical feedback amplifier |
US5184247A (en) * | 1989-07-17 | 1993-02-02 | Siemens Aktiengesellschaft | Optically stabilized feedback amplifier |
EP0484923A2 (en) * | 1990-11-07 | 1992-05-13 | Nippon Telegraph And Telephone Corporation | Semiconductor wavelength conversion device |
EP0484923A3 (en) * | 1990-11-07 | 1992-06-03 | Nippon Telegraph And Telephone Corporation | Semiconductor wavelength conversion device |
US5155737A (en) * | 1990-11-07 | 1992-10-13 | Nippon Telegraph & Telephone Corporation | Semiconductor wavelength conversion device |
DE4301830A1 (en) * | 1993-01-23 | 1994-07-28 | Ant Nachrichtentech | 3-section DFB semiconductor laser with extended wavelength tuning range |
WO2003009438A2 (en) * | 2001-07-18 | 2003-01-30 | Marconi Uk Intellectual Property Ltd | Wavelength division multiplex optical wavelength converter |
WO2003009438A3 (en) * | 2001-07-18 | 2004-02-12 | Marconi Uk Intellectual Prop | Wavelength division multiplex optical wavelength converter |
Also Published As
Publication number | Publication date |
---|---|
JPS63244783A (en) | 1988-10-12 |
JPH0656908B2 (en) | 1994-07-27 |
EP0285393A3 (en) | 1989-07-26 |
EP0285393B1 (en) | 1993-06-16 |
DE3881737T2 (en) | 1993-12-02 |
DE3881737D1 (en) | 1993-07-22 |
US4856005A (en) | 1989-08-08 |
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